Even the highest-quality mattress will wear out in time. You can prolong the life of your mattress by flipping it often (Bruce Barman recommends four flips a year), but soon comes the day when it's time to say goodbye. How do you know when it's time to ditch the old mattress and invest in something new? The Better Sleep Council suggests you ask yourself these questions:

• Do you wake up sore or stiff, or with back pain?
• Does the surface of your mattress look uneven?
• Are there sagging spots where you lie, or around the edges of the mattress? Are some spots more comfortable than others?
• When you roll around, do you hear creaks or crunches? Does the bed wobble or sway?
• If you sleep with a partner, do you both roll toward the middle of the bed?
• Have you used the bed nightly, for eight to 10 years?

If you answered yes to any of these questions, it might be time to think about shopping for a new sleep set. If you do, remember to shop for value, not by price.